It is highly desirable to provide copper base alloys having high strength properties and favorable strength to ductility characteristics. It is particularly desirable to provide low cost hot and cold workable copper base alloys which are characterized by high mechanical strength, favorable strength to ductility combinations and excellent formability characteristics. It is especially desirable to provide copper base alloys characterized as aforesaid which are convenient to process and which may be made economically on a commercial scale.
It is highly desirable to provide alloys of the foregoing type which satisfy the stringent requirements imposed by modern applications for electrical contact springs in which high strength is required coupled with good bend formability as well as resistance to mechanical property degradation at moderately elevated temperatures, such as stress relaxation resistance.
Commercially, copper alloys tend to be deficient in one or more of the foregoing characteristics. For example, the commercial copper Alloy 510 (a phosphor-bronze containing from 3.5 to 5.8% tin and from 0.03 to 0.35% phosphorus) is superior in strength but poor in bend characteristics. The commercial copper Alloy 725 (a copper-nickel containing 8.5 to 10.5% nickel and 1.8 to 2.8% tin) is superior with respect to bend properties, solderability and contact resistance, but deficient in strength.
The present invention relates to the preparation of spinodal, precipitation hardened copper base alloys having an unusual combination of properties based on a composition containing from 10 to 30% nickel and from 1 to 5% aluminum. Nickel-aluminum containing copper base alloys are known in the art, such as disclosed in U.S. Pat. Nos. 2,101,087, 2,101,626 and 3,399,057; however, these teachings do not contemplate the preparation of spinodal, precipitation hardened copper alloys having finely dispersed precipitates of Ni.sub.3 Al particles as disclosed in the present invention.
Accordingly, it is a principal object of the present invention to provide a method for the preparation of improved copper base alloys having high strength and favorable strength to ductility characteristics.
It is a further object of the present invention to provide a method for preparing an improved copper base alloy as aforesaid which has other good properties, such as excellent formability characteristics in the precipitation hardened condition and resistance to mechanical property degradation at moderately elevated temperatures, such as stress relaxation resistance.
It is a still further object of the present invention to provide a method for preparing an improved copper base alloy as aforesaid which is convenient and economical to prepare on a commercial scale.
Further objects and advantages of the present invention will appear hereinbelow.